Run-off water and wastewater generally contain pollutants and contaminants that have adverse effects on the environment and the surroundings. Therefore, many environmental laws and regulations require run-off water and wastewater to be treated in developed areas before being discharged into a body of water, such as a stream or river. Many water treatment systems are presently known in the art. However, the water treatment systems currently known generally require large amounts of space, are ineffective at treating large volumes of heavily polluted or contaminated water, and cannot easily and effectively eliminate certain bacteria, such as Escherichia coli. 
Thus, a need exists for a flexible and scalable water treatment system and method for treatment of run-off water and wastewater that is capable of treating large quantities of heavily polluted water in a limited area while also removing various contaminants and eliminating bacteria.